You keep saying that, and in many cases (including this one) that may be true. However, there are in-fact transmissions that are designed to be serviced only (or mainly) by fluid exchange machine. The ones in my two cars are examples of such. They are sealed, have no dip-sticks, and the factory service manual calls for the use of a fluid exchange machine to change out the fluid. The factory service interval is 150K miles, so it is very important that all of the fluid, not just 30% of it, be changed.